This invention proposes a linear actuator of the screw and/or circulating ball type, in which the nut is joined at the head ends with closure walls which serve also as thrust bearing rings and have, on the inside have channels connecting the helicoidal thread of the screw-nut coupling with a channel for the return of the balls.
To ensure the required precision without resorting to complicated working, both the nut and the walls of the head are sintered.
In various fields of mechanical engineering, circulating ball actuators are used which include a nut consisting of a body which is basically cylindrical, rotated about its axis and held along its axis, and a rotating screw which is constrained along its axis inside said actuator.
The nut screw coupling occurs through a number of ball bearings which move along a helicoidal groove in the external surface of the screw and on the internal surface of the nut.
In some of these actuators the return path of the ball consists of a tubular element which runs externally of the nut.
In other versions a pair of holes are made in the nut and two plugs are inserted which are shaped and calibrated for the passage of the balls, thus joining the return channel to the helicoidal groove.
From the point of view of construction, this work is rather complicated, requiring a number of precision processes for the various parts to be assembled exactly. This is even more so when one considers that these actuators must work to be very strict tolerance to the order of a few hundredths of a millimeter.
On the other hand screw and/or circulating ball actuators are quite compact, requiring a low power motor, and are thus highly suited to use in a number of applications where production may be possible at considerably lower cost than for the current devices.